Cashco 964 - Manual (Page 12)

IOM-964 12
Theoretical ____________________ psig
Bench Setting
from Nameplate ____________________ Barg
______________________ psig
Setting at “S”
Position ______________________ Barg
______________________ psig
Setting at “O”
Position ______________________ Barg
b. Increase combined stem (3, 19) length
by ro tat ing the valve stem (3) CCW
(viewed from plug end) a dis tance equal
to the amount of overtravel. Retighten
jam nut (18).
9 a. If travel indicator stops below the “O” po si-
tion, the com bined stem (3,19) length is
long. Loos en jam nut (18) holding in di ca tor
disc (20) against ac tu a tor stem (19).
b. Decrease combined stem (3, 19) length
by rotating the valve stem (3) CW (viewed
from plug end) a distance equal to the
amount of undertravel. Retighten jam
nut (18).
10. Confi rm that the position at the indicator disc
(20) align with the indicator plate (21) at the
“O” position.
11. Release air pressure in actuator allowing valve
stem (3) to travel to the closed or “S” position.
Check the position in di cat ed on the indicator
plate (21).
12. If the “S” closed position is not correct, repeat
steps 8 through 11 until the combined stem
(3,19) length is correct.
13. Pressurize the actuator to a pressure level
corresponding to the lower pres sure lev el of
the bench set ting; i.e. for 5-15 psig (.34-1.0
Barg) range, set pres sure at 5 psig (.34 Barg).
Do the pres sur iza tion slowly while observing
the indicator disc (20) and indicator plate (21)
simultaneously.
14. The proper calibration of the ac tu a tor/valve unit
will occur when, at the lower pressure level of
bench setting, the valve stem as sem bly's (3)
plug will just begin to travel from the closed
po si tion.
Pressurize actuator slowly. If plug (3) begins
travel before reach ing the lower pres sure level
of bench setting, then in crease the ac tu a tor's
range spring (6) com pres sion by wrench
tight en ing spring ad jus tor (4) CW (viewed
from plug end) in 1/2 revolution in cre ments
until desired bench setting is reached.
Pressurize actuator slowly. If plug (3) begins
travel after surpassing the lower pres sure lev el
of bench setting, then re duce the ac tu a tor’s
range spring (6) com pres sion by wrench
loos en ing spring ad jus tor (4) CCW (viewed
from plug end) in 1/2 rev o lu tion in cre ments
until desired bench set ting is reached.
15. Increase pressure to actuator up to the upper
level of bench setting and ob serve valve plug
(3) position at the in di ca tor plate (21). The
valve plug (3) should be within ±8% (of full
“stroke”) of the “O” (for “open”) position of
the in di ca tor plate (21). (“Stroke” length is
in di cat ed on the name plate (12), and is the
dis tance be tween the “S” and “O” points of
the in di ca tor plate (21).)
16. Record here the theoretical and ac tu al pres-
sure levels of paragraphs 14 and 15.
17. Tighten second stem jam nut (18).
C. Procedure - Direct Action, ATC-FO:
1. Place body (1) in a vise with ac tu a tor as-
sem bly (AA) directed upwards.
2. Connect a temporary air supply with an in-
line ad just able air set regulator with gauge
to the ac tu a tor top works con nec tion.
3. Loosen lower stem jam nut (18) by ro tat ing
CCW (viewed from plug end) 2-3 revolutions.
Using upper stem jam nut (18), fi rmly lo cate
the in di ca tor disc (20) up against the ac tu a tor
stem (19) bottom. With no pres sure in the
actuator, the up wards trav el is halted by the
ac tu a tor's in ter nal upstop mech a nism.
4. Loosen screws (22) and po si tion the in di ca tor
plate (21) at “O” (for open); tight en screws
(22) to secure in di ca tor plate (21). (NOTE:
Set the indicator plate (21) at the top edge
of the in di ca tor disc (20).)
5. Reference the nameplate (12) at tached to
the actuator yoke (1). De ter mine the bench
set ting of the in stalled range spring (6) from
the name plate (12); i.e. 3-13 psig (.20-.90
Barg), or 6-27 psig (.41-1.9 Barg).
6. Pressurize the actuator to a level 2-3 psig
(0.1-0.2 Barg) above the upper pres sure
level of the bench setting; i.e. for 3-13 psig
(.20-.90 Barg) range, set pres sure at 15-16
psig (1.0-1.1 Barg).